U.S. patent application number 10/589258 was filed with the patent office on 2007-11-29 for cutting tool and insert with serrated contact surfaces between holder and insert.
Invention is credited to Goran Pantzar.
Application Number | 20070274792 10/589258 |
Document ID | / |
Family ID | 31989588 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070274792 |
Kind Code |
A1 |
Pantzar; Goran |
November 29, 2007 |
Cutting Tool and Insert with Serrated Contact Surfaces Between
Holder and Insert
Abstract
The invention relates to a cutting tool of the type that
comprises, on one hand, a basic body (1) having an insert seat, and
on the other hand a cutting insert (2), which is detachably
connected in the insert seat and rigidly secured in the same by
means of connecting surfaces (3, 5) of serration type, one (3) of
which forms said insert seat and comprises first and second ridges
(18, 19), which extends perpendicularly to each other. According to
the invention, at least the connecting surface that forms the
insert seat (3) is formed with, on one hand, two spaced-apart
surface fields or sets of a plurality of mutually parallel, first
ridges (18A, 18B), which are arranged in extension of each other,
and on the other hand one or more second, transverse ridges (19),
which are located between the two sets of first ridges (18A, 18B).
Furthermore, the invention also relates to a basic body of a
cutting tool, as well as a cutting insert as such.
Inventors: |
Pantzar; Goran; (Arsunda,
SE) |
Correspondence
Address: |
DRINKER BIDDLE & REATH (DC)
1500 K STREET, N.W.
SUITE 1100
WASHINGTON
DC
20005-1209
US
|
Family ID: |
31989588 |
Appl. No.: |
10/589258 |
Filed: |
February 22, 2005 |
PCT Filed: |
February 22, 2005 |
PCT NO: |
PCT/SE05/00244 |
371 Date: |
May 16, 2007 |
Current U.S.
Class: |
407/66 |
Current CPC
Class: |
B23C 2200/165 20130101;
B23C 2260/80 20130101; Y10T 407/1906 20150115; B23C 2210/168
20130101; B23C 5/2221 20130101; Y10T 407/22 20150115; Y10T 407/23
20150115 |
Class at
Publication: |
407/066 |
International
Class: |
B23B 27/16 20060101
B23B027/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 24, 2004 |
SE |
0400420-6 |
Claims
1. Cutting tool comprising, on one hand, a basic body (1) having an
insert seat, and on the other hand a cutting insert (2), which is
detachably connected in the insert seat and rigidly secured in the
same by means of connecting surfaces (3, 5) of serration type, one
of which forms said insert seat (3), and comprises first and second
ridges (18, 19), which extend perpendicularly to each other,
characterized in that at least the connecting surface that forms
the insert seat (3) comprises, on one hand, two spaced-apart
surface fields or sets (A, B) of a plurality of mutually parallel,
first ridges (18A, 18B), which are arranged in extension of each
other, and on the other hand one or more second, transverse ridges
(19), which are located between the two sets of first ridges (18A,
18B).
2. Basic body of a cutting tool, comprising a connecting surface
(3) of serration type serving as insert seat, in which connecting
surface first and second ridges (18, 19) are included, which extend
perpendicularly to each other in order to guarantee mechanical
locking in two directions perpendicular to each other,
characterized in that the connecting surface (3) comprises, on one
hand, two spaced-apart sets (A, B) of a plurality of mutually
parallel, first ridges (18A, 18B), which are arranged in extension
of each other, and on the other hand one or more second, transverse
ridges (19), which are located between the two sets of first ridges
(18A, 18B).
3. Basic body according to claim 2, characterized in that at least
crests (21) of the first and second ridges (18A, 18B, 19) are
located in a common plane.
4. Basic body according to claim 3, characterized in that between
an individual transverse ridge (19) and a nearby set of first
ridges (18A, 18B), a third type of serrations are formed in the
form of a plurality of tops (24), which are located in a row (19A,
19B) parallel to the transverse ridge, and are mutually spaced
apart by extensions (24) of the grooves (22) that separate said
first ridges (18A, 18B) laterally.
5. Basic body according to claim 2, characterized in that at least
the crest (21) of the transverse ridge or ridges (19) are situated
in another plane than the crests (21) of the first ridges (18A,
18B).
6. Basic body according to claim 5, characterized in that the
transverse ridge or ridges (19) are countersunk in relation to the
first ridges (18A, 18B).
7. Basic body according to claim 6, characterized in that the
transverse ridge or ridges (19) are countersunk to a level on which
their crests are in or below an imaginary plane in which the
bottoms (23) of the grooves (22) positioned between the first
ridges (18A, 18B) are located.
8. Cutting insert of a cutting tool, comprising a connecting
surface (5) of serration type, in which ridges are included, which
are delimited by intermediate grooves, characterized in that the
connecting surface (5) comprises, on one hand, two spaced-apart
sets of a plurality of mutually parallel, first ridges (18A, 18B),
which are arranged in extension of each other, and on the other
hand one or more second, transverse ridges or tops (19, 16), which
are located between the two sets of first ridges (18A, 18B).
Description
TECHNICAL FIELD OF THE INVENTION
[0001] In a first aspect, this invention relates to a cutting tool
intended for chip-removing machining of the type that comprises, on
one hand, a basic body having an insert seat, and on the other hand
a cutting insert, which is detachably connected in the insert seat
and rigidly secured in the same by means of connecting surfaces of
serration type, one of which forms said insert seat and comprises
first and second ridges, which extend perpendicularly to each
other.
[0002] In practice, the basic body may consist of, for instance, a
drill shank or a cutter head, and the cutting insert of an
indexable cutting insert.
PRIOR ART
[0003] A cutting tool of the above-mentioned type is previously
known by WO 9900208 A1. In this case, the serration connecting
surface serving as insert seat comprises two sets of ridges, which
each are located in a separate surface field. This disposition of
the ridges in only two sets or surface fields leads to the
disadvantage that the cutting forces, which act on the cutting
insert, are not distributed in a desirable, even way along the
entire area of the connecting surface; something which means that
the ability of the connecting surface to carry and resist large
forces becomes limited. In, for instance, four-edged cutting
inserts of the type that are indexable in four positions, the
corner of the cutting insert that is indexed forward to an active
position, accordingly, gets a tendency to be displaced; something
which among other things may lead to mediocre machining precision
as a consequence of the cutting insert being dislodged from the
desired position thereof.
OBJECTS AND FEATURES OF THE INVENTION
[0004] The present invention aims at obviating the above-mentioned
disadvantages of the previously known cutting tool and at providing
an improved cutting tool. Therefore, a primary object of the
invention is to provide a cutting tool, the serration connection of
which between the basic body and a cutting insert guarantees an
even and reliable distribution of the cutting forces acting on the
cutting insert along the entire surface extension of the
connection. It is also an object to provide a cutting tool, the
serration connection of which--for a given tool dimension--can
carry larger forces than the previously known serration connection,
without being dislodged from the fixed, exact position thereof.
[0005] According to the invention, these objects are attained by
means of the features defined in the characterizing portion of
claim 1.
[0006] In a second aspect, the invention also relates to a basic
body as such intended for cutting tools. The features of the basic
body according to the invention are seen in the independent claim
2. Preferred embodiments of the basic body according to the
invention are further defined in the dependent claims 3-7.
[0007] In a third aspect, the invention also relates to a cutting
insert as such intended for cutting tools. The features of this
cutting insert are seen in the independent claim 8.
BRIEF DESCRIPTION OF THE APPENDED DRAWINGS
[0008] In the drawings:
[0009] FIG. 1 is a simplified perspective view showing a cutting
tool, the basic body of which consists of a cutter head having an
insert seat, in which a cutting insert is fixed,
[0010] FIG. 2 is an end view showing the interface between the
cutting insert and the insert seat on an enlarged scale,
[0011] FIG. 3 is an enlarged, perspective exploded view showing the
insert seat as well as the bottom side of the cutting insert,
[0012] FIG. 4 is a schematic perspective view of an insert seat
according to the invention,
[0013] FIG. 5 is a perspective exploded view showing an alternative
embodiment of a serration connection between a cutting insert and
an insert seat, and
[0014] FIG. 6 is a perspective view from below of a cutting insert
according to the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0015] In FIG. 1, a rotatable cutting tool is shown exemplified as
a milling cutter, which comprises a basic body 1, in the form of a
cutter head, as well as a number of cutting inserts 2. For the sake
of simplicity, only one such cutting insert is shown, although
milling cutters in practice are provided with a plurality of
peripherical and tangentially spaced cutting inserts. The
individual cutting insert 2 is mounted in an insert seat designated
3, which is formed adjacent to a chip pocket 4 in the periphery of
the basic body 1. The insert seat 3 consists of a first connecting
surface of serration type, which is arranged to co-operate with a
second serration connecting surface 5 (see FIGS. 2 and 3), which is
formed on the bottom side of the cutting insert 2. The cutting
insert 2 is fixed in the insert seat 3 by means of a suitable
clamping member, which in the example consists of a screw 6, but
which also may consist of a clamp or the like.
[0016] Before the two serration connecting surfaces 3, 5 are
described closer, the general shape of the basic body 1 as well as
of the cutting insert 2 should be briefly described. In the chosen
example, the cutting insert 2 (see FIGS. 2 and 3) has a flat and
quadrangular (square) basic shape, which is defined by generally
planar and mutually parallel top and bottom sides 7, 8. Between
these, four side surfaces 9 extend, which are similar and form
clearance surfaces adjacent to cutting edges 10, 11, which are
formed between the top side 7 and the side surfaces 9.
[0017] The cutter head 1 serving as basic body (see FIG. 1) has a
ring-shaped front surface 12 and a rotationally symmetric envelope
surface 13. Rearward from the main portion of the cutter head, a
tapering portion 14 extends for the attachment in a tool holder. In
FIG. 1, 15 designates the corner of the cutting insert, which is
indexed forward to an active position. In this state, the edge 10
forms a major cutting edge and the edge 11 a minor cutting edge or
wiper edge. It is axiomatic that the corner 15 indexed forward is
exposed to the major part of the forces acting on the cutting
insert during operation, while the other three corners, which are
inactive, are not exposed to any substantial stresses.
[0018] Each one of the connecting surfaces 3 and 5 comprises in a
conventional way a number of ridges and/or tops, which are mutually
spaced apart by grooves. In the same way as in WO 9900208 A1, the
connecting surface 5 of the exemplified cutting insert 2 is
waffle-patterned or chequered, so far that the same comprises
pyramidal tops 16 arranged in rows, which are uniform and spaced
apart by grooves 17, 17', which extend perpendicularly to each
other. The serration connecting surface 3 serving as insert seat
comprises two different kinds of ridges generally designated 18 and
19, respectively, which extend perpendicularly to each other in
order to guarantee mechanical locking of the cutting insert in two
directions perpendicular to each other. The grooves positioned
between the ridges 18 are designated 22. The cross-section shape of
the ridges is conventional so far that the individual ridge is
delimited by two opposed flank surfaces or flanks 20 (see FIG. 2),
between which there is a crest 21, which forms the highest located
portion of the ridge. Nearby ridges are laterally spaced apart by
grooves 22, the bottoms of which are designated 23. A common angle
between the flank surfaces 20 is 60.degree., although also other
angles are feasible. It is essential that the crests of the ridges
in one of the connecting surfaces do not bottom in the grooves in
the other connecting surface. It is also essential that the pitch
between the ridges is the same in the two connecting surfaces,
because otherwise one of the connecting surfaces would not be able
to be fit into the other.
[0019] As far as the shown serration connection between the cutting
insert and the insert seat has been described hitherto, the same is
in all essentials previously known by WO 9900208 A1.
[0020] New and characteristic of the present invention is that at
least the connecting surface 3, which forms an insert seat in the
basic body, comprises, on one hand, two spaced-apart sets of a
plurality of mutually parallel, first ridges 18, which are arranged
in extension of each other, and on the other hand one or more
second, transverse ridges 19, which are located between the two
sets of first ridges. In FIG. 4, a surface field, which comprises a
first set of first ridges 18, is designated A, while a surface
field spaced apart from the same and comprising a second set of
first ridges 18 is designated B. As a consequence of this, the
ridges in the first-mentioned field are designated 18A, while
homologous ridges in the surface field B are designated 18B.
Furthermore, in FIG. 4, 15A designates the corner in the insert
seat, toward which the active corner 15 of the cutting insert 2 is
turned in fixed position.
[0021] Reference being made to FIG. 1, it should be pointed out
that the cutting insert 2 during operation is exposed to forces in
three different directions in a conceived system of coordinates,
namely tangential forces in the x direction, radial forces in the y
direction and axial forces in the z direction. Of said forces, the
radial forces in the y direction are considerably larger than the
axial forces in the z direction.
[0022] Now reference is made again to FIG. 4, which illustrates how
the number of ridges 18A, 18B in the surface fields A, B is
considerably larger than the number of transverse ridges or
intermediate ridges 19. Thus, in the example, the number of ridges
18A and 18B, respectively, amounts to twelve, while the number of
transverse ridges 19 amounts to two. This means that the main part
of the cutting forces acting on the cutting insert, namely the
radial forces y, are carried by a large number of ridges via the
force-transferring flanks thereof, the total area of which is many
times larger than the total area of the flanks of the transverse
ridges 19, which have the purpose of carrying the axial forces in
the z direction. In this connection, it should be pointed out that
surface contact for the transfer of force in the y direction
essentially is established between, on one hand, the radially
outwardly turned flank on each ridge 18A, 18B, and on the other
hand the radially inwardly turned flank on each top 16 in the
connecting surface 5 of the cutting insert. Surface contact for the
transfer of force in the z direction, in turn, is established
between, on one hand, the flank on each transverse ridge 19 that is
facing the front surface 12 of the basic body, and on the other
hand the flanks on the tops 16 of the waffle pattern that are
turned away from said front surface. By the fact that the ridges 18
that should carry the dominant radial forces y are present not only
adjacent to the corner 15A (in the surface field A), but also in
the surface field B distanced from the corner in question, the
capability of the connecting surface to resist the forces that aim
to turn the cutting insert in relation to the insert seat, more
precisely around a centre of rotation at the corner 15A, is
radically improved.
Manufacture of the Tool
[0023] Of the two parts 1, 2, which together form the cutting tool,
the basic body 1 is made from steel or the like, the serration
connecting surface 3 being produced by precision machining, in
particular milling, of the ridges and grooves that together form
the surface in question. However, the individual cutting insert 2
is made by compression moulding and sintering of cemented carbide
(or another material having considerably larger hardness and
resistance to wear than steel), the connecting surface 5 on the
bottom side of the cutting insert obtaining at least the basic
shape thereof in connection with the pressing and sintering. In
practice, the cutting insert may either be of the directly pressed
type, i.e., lack after-treatment, or be ground in order to attain
high precision.
[0024] Milling of the serration connecting surface 3 shown in FIG.
4 in the basic body may be carried out in various ways. One way is
to initially produce the ridges 18A and 18B in two consecutive
steps, between which an intermediate step is performed in which a
milling cutter suitable for the purpose is raised in order to leave
a central area on the cutting insert. For instance, the ridges 18A
in the surface field A may first be formed by the milling cutter
being brought in a horizontal plane. When the ridges have received
the full length, the milling cutter is raised and jumps over or
skips the central area, after which it once again is lowered down
into the same plane as the first-mentioned one, in order to
complete ridges 18B with the desired length. In another operation,
another milling cutter, the shape of which is suitable for the
provision of the transverse ridges 19, is brought along the bottom
side of the cutting insert, more precisely perpendicularly to the
feeding direction of the first milling cutter. In doing so, the two
ridges 19 are produced, which extend between opposed side surfaces
of the cutting insert. Between each individual transverse ridge 19
and a nearby set of longitudinal ridges 18A, 18B, secondary
transverse ridges 19A and 19B, respectively, are also present.
These ridges do not have full cross-section along the entire length
thereof, but are intersected by more or less deep part slots 24,
which constitute extensions of the grooves 22, and are produced in
connection with raising and lowering, respectively, of the first
milling cutter, which creates the ridges 18A, 18B. By the existence
of these countersinks 24, the male-like formations 19A, 19B obtains
at least partly the character of pyramid-like tops, rather than
continuous ridges.
[0025] It is of course also feasible to form the sets of ridges in
the opposite order, i.e., first the transverse ridges 19 and then
the longitudinal ridges 18.
[0026] In the embodiment shown in FIG. 4, all ridges are equally
high. More precisely, the crests 21 on all ridges 18A, 18B, 19, 19A
and 19B are located in a common plane (that is parallel to the top
side 7 of the cutting insert). However, it is also feasible to
locate the ridges, or at least the crests thereof, in different
planes. One such embodiment is exemplified in FIG. 5, in which a
number of transverse ridges 19 in the connecting surface 3 serving
as insert seat are located in another plane than the ridges 18A,
18B. More precisely, the transverse ridges 19 are countersunk in
relation to the longitudinal ridges 18A, 18B. It should be made
clear that the level difference between the respective ridges
primarily consists of the crests of the ridges being located in
different planes. This may be the case even if the ridges in the
respective surface fields have different depth or height. The
embodiment shown in FIG. 5 is particularly advantageous, so far
that the crests of the ridges 19 are located in flush with or under
the bottoms of the grooves 22, which are present between the ridges
18A, 18B. In such a way, the manufacture can be carried out without
any jumping motions of the milling cutter. Thus, in a first
operation, it is possible to bring the milling cutter in one plane
from one end of the insert seat to the opposite, after which a
second milling cutter is brought to move perpendicularly to, and on
a lower level than the first milling cutter, so as to form the
transverse ridges 19. In doing so, in the basic body, a central
countersink 25 is formed, which along opposed edges is delimited by
shoulder surfaces 26. If desired, said shoulder surfaces 26 may be
utilized for purposes of transfer of force by being formed with
close fit in relation to two edge surfaces 27 on a female portion
28 protruding from the bottom side of the cutting insert, which
female portion carries transverse ridges 19 and has the same basic
shape as the countersink 25.
[0027] In the example according to FIG. 5, the cutting insert 2 is
indexable in only two positions. For this reason, instead of a
waffle-patterned serration connecting surface, a connecting surface
5 may be used that, like the insert seat 3, comprises two mutually
spaced-apart sets of longitudinal ridges 18A, 18B, as well as
transverse ridges 19 between the same, the transverse ridges 19
being formed on the female portion 28.
[0028] Finally, in FIG. 6, an alternative embodiment of a cutting
insert 2 is shown, which on the bottom side thereof has two
spaced-apart sets of longitudinal ridges 18A, 18B, as well as one
set of pyramidal tops 16, which are arranged in a plurality of
(five) transverse rows for the co-operation with complementary
transverse ridges 19 in an insert seat 3.
[0029] The number of longitudinal and transverse ridges,
respectively, in the sets of ridges, which together form a
serration connecting surface, may vary most considerably. However,
generally, the number of longitudinal ridges should be considerably
larger than the number of transverse ridges. In practice, the
number of longitudinal ridges may, accordingly, be at least 10, or
even 20 times larger than the number of transverse ridges. This is
for the total area of the active flanks of the longitudinal ridges
(one on each individual ridge) to become many times larger than the
total area of the force-carrying flanks of the transverse ridge or
ridges. The number of transverse ridges may advantageously be as
small as 1, although also variants of 2-6 transverse ridges are
feasible, as has been exemplified in the drawings. The absolute
number of longitudinal ridges in each one of the two surface fields
A, B may advantageously amount to 10 or more.
LIST OF REFERENCE DESIGNATIONS
[0030] 1=basic body [0031] 2=cutting insert [0032] 3=serration
connecting surface (insert seat) [0033] 4=chip pocket [0034]
5=serration connecting surface (on cutting insert) [0035] 6=screw
[0036] 7=top side of cutting insert [0037] 8=bottom side of cutting
insert [0038] 9=side surfaces [0039] 10=major cutting edge [0040]
11=wiper edge [0041] 12=front surface [0042] 13=envelope surface
[0043] 14=fixing portion [0044] 15=active corner on cutting insert
[0045] 15A=corner in insert seat [0046] 16=serration tops [0047]
17=grooves [0048] 18=longitudinal ridges [0049] 19=transverse
ridges [0050] 20=flanks of ridge [0051] 21=crest of ridge [0052]
22=grooves [0053] 23=bottom of groove [0054] 24=slots of groove
[0055] 25=countersink in insert seat [0056] 26=shoulder surfaces
[0057] 27=edge surfaces [0058] 28=female portion
* * * * *